Barrier films for blocking external components such as oxygen and moisture are used not only for packaging materials of foods or medicines, and the like which are conventional main applications, but also members for FPDs (flat panel displays) such as LCDs (Liquid Crystal Displays) or solar cells, substrates for electronic papers or OLEDs (Organic Light Emitting Diodes) or sealing films, and the like.
In the applications, high barrier characteristics are required, and from the viewpoint of performance guarantee, moisture-heat resistance, in which the barrier characteristics are not lowered even after being left under moisture and heat conditions, and the like are also required.
As one of methods for preparing barrier films by a wet method, there is known a method of converting a polysilazane layer coated on a base material film to silica. In this method, the polysilazane can be converted to silica by being heat-treated in the presence of oxygen or water vapor, or through hydrolysis or dehydration polycondensation.
For example, in Patent Document 1, a method is described, in which perhydropolysilazane or a modified product thereof is applied to a base material film and calcined under vacuum.